This invention relates to heavy-duty off-road trucks and, more particularly, to a tailgate assembly for these trucks.
The dump bodies of heavy-duty, off-road trucks are often provided with tailgate assemblies in order to increase their load capacity. A tailgate assembly typically includes a pair of straight sidearms which are pivotally mounted to the sides of the dump body and between which a center-rear portion is supported. When the tailgate assembly is in a closed position, the center-rear portion closes off the rear end of the dump body. Thus, when the tailgate assembly is closed, the effective volumetric capacity of the dump body is increased as material is prevented from spilling out of the rear of the dump body. Such tailgate assemblies are subjected to a significant amount of punishment and thus must have a strong and durable design. One way in which this is accomplished is by welding reinforcing structures onto the sidearms and center-rear portion. As will be appreciated, however, this is a very time-consuming process.
Another area of concern with respect to the strength of the tailgate assembly is the connections between the sidearms and the center-rear portion. There are two different ways in which the center-rear portion is connected to the sidearms. Specifically, according to a first connection method, each end of the center-rear portion butts up against the inside surface of a respective one of the sidearms. Typically, a flange is provided on each end of the center-rear portion which extends along the inside surface of the respective sidearm. The center-rear portion is secured at either end to the arms by bolts which extend through the respective sidearm and flange in a direction parallel to the center-rear portion and perpendicular to the sidearm. Alternatively, the center-rear portion is secured at either end to the sidearms by welding.
With the other connection method, the arrangement of the center-rear portion and the sidearms is reversed. In particular, the inside surface of the center-rear portion butts up against the ends of the sidearms. A flange is provided on the end of each sidearm that extends along the inside surface of the center-rear portion. The center-rear portion is secured to the sidearms by bolts which extend through the center-rear portion and the flanges in a direction parallel to the sidearms and perpendicular to the center-rear portion or by welding this joint.
A significant drawback with both of these bolted, or in some cases welded, connection arrangements is that the connections compromise the durability of the tailgate assembly. Specifically, during loading of the dump body and when the truck is travelling up an incline, the load material frequently rolls or slides against the center-rear portion of the tailgate assembly, subjecting it to a significant amount of punishment. By virtue of their arrangement, the nuts and bolts used to connect the center-rear portion to the sidearms or the welded joints are responsible for transmitting the forces applied against the center-rear portion to the sidearms. Unfortunately, the nuts and bolts and/or the welding of the connection are/is ill equipped to perform this task as they have difficulty withstanding the forces involved. As a result, the center-rear portion is susceptible to becoming separated from the sidearms after repeated use necessitating costly repairs or even replacement.
Another drawback with the first connection arrangement is that it makes it difficult to compensate for any variations in width between the center-rear portion and the dump body. If the center-rear portion is not precisely matched to the width of the dump body, shims must be used at the connections between the center-rear portion and the sidearms. Fabricating and assembling these shims, can make the assembly process significantly more time consuming and difficult.
Moreover, as a result of the need to use flanges on the ends of either the sidearms or center-rear portion, it can be difficult to fit the bottom edge of the center-rear portion tightly against the rear end of the floor of the dump body when using the conventional connection arrangements while still providing the needed clearance for operation of the tailgate. Thus, a gap frequently exists between the bottom edge of the center-rear portion and the rear end of the floor of the dump body through which the load material can spill.
Accordingly, in view of the foregoing, a general object of the present invention is to provide a tailgate assembly for a heavy-duty, off-road truck which is stronger and more durable than tailgate assemblies that are presently commercially available.
Another object of one embodiment of the present invention is to provide a tailgate assembly for a heavy-duty, off-road truck which can be readily adjusted to compensate for variations in width between the center-rear portion and the dump body and which provides a tight fit between the bottom edge of the center-rear portion and the rear of the dump body floor.
Another object of one embodiment of the present invention is to provide a tailgate assembly for a heavy-duty, off-road truck which is less time-consuming to manufacture and easier to assemble to a dump body.
These and other features and advantages of the invention will be more readily apparent upon reading the following description of an exemplary embodiment of the present invention and upon reference to the accompanying drawings wherein: